The present invention is directed to fruit and vegetable produce. More specifically, the present invention is directed toward an enzymatic method of improving the aesthetic appearance of produce which has been cut or peeled. The present invention is further directed to prolonging the shelf-purchase life of produce which has been cut or peeled.
The newly exposed surfaces of many articles of produce are subject to dehydration within a short period of time after being exposed. The surface of produce may be exposed by cutting, peeling or a combination thereof. Often times, the peeled surface of produce is affected to a greater extent because of the usually larger surface areas involved. Specifically, the entire surface of peeled produce is subject to dehydration rather than solely the cut edge. The dehydration manifests itself as a whitening of the produce at the cut edge or peeled surface which has been exposed. The problem is most pronounced on produce that has been abrasively peeled. Consumers tend to associate this appearance with aged or non-fresh produce. Hence, the dehydration problem significantly reduces the aesthetic appearance, quality, and more importantly, the shelf-purchase life of the produce.
A paper presented by Tatsumi at the 1989 annual meeting of the American Society of Horticultural Sciences suggests that the dehydration is caused by the presence of cell wall fragments that occur on the cut surfaces of vegetables. Scanning Electron Microscopy (SEM) was used by Tatsumi to verify the presence of these cell wall fragments on cut produce. The cell wall fragments appear to be caused by the mechanical shearing forces created by a knife as it cuts the vegetable. This paper did not examine peeled vegetables, but it is very likely that similar mechanical forces are responsible for the dehydration seen in this method of processing produce.
SEM investigation of produce items that have either been cut or peeled reveal the presence of cell wall fragments on the newly exposed surfaces Tatsumi suggested using razor blades instead of knives to cut the produce as a remedy for the dehydration problem since the razor sharp blade would leave a less fragmented edge than would a knife. However this approach is not practical for cutting produce on a commercial scale since the produce is handled by mechanical cutters. Also, Tatsumi did not propose any solution to the dehydration problem on the surfaces of produce which have been exposed by peeling.
Bruemmer (U.S. Pat. No. 4,284,651) discloses the use of mixtures of cellulase and pectinase to dissolve the albedo of citrus fruit in order to facilitate peeling. Albedo is the sticky white tissue between the rind and the juice sections of citrus fruit The thick peel of the citrus fruit is first carefully scored so as to penetrate the albedo while not cutting into the juice sections The enzyme mixture is then vacuum infused into the albedo and allowed to react for a period of time. After sufficient incubation, the peel nearly falls off of the otherwise intact citrus fruit which is then washed and packaged prior to being stored in refrigeration.
Hase (U.S. Pat. No. 4,214,007) and Murata (U.S. Pat. No. 4,333,955) disclose a method of processing dried beans as instant food. One of the steps in processing the raw beans is an enzymatic treatment with cellulase or a mixture of cellulase and pectinase. The treatment serves to partially destroy the cell wall of the beans. The beans, once processed, are capable of being instantly reconstituted to an edible condition with the addition of boiling water. The enzyme treatment is cited as increasing the beans' permeability to the boiling water when the beans are being reconstituted for consumption.
Guigou (French Pat. No. 2,207,657) discloses the use of a commercially available enzyme preparation which contains various pectinases and cellulases to eliminate the peel or skin of fruits and vegetables by enzymatic hydrolysis. The enzyme is deactivated during the pasteurization step in the processing of the fruit or vegetable. The enzyme treatment is cited as increasing throughput while reducing labor input and decreasing waste generated by traditional methods of peeling.
At present, no one has attempted to rectify the problem of produce dehydration in a manner similar to that of the present invention. The only related use of enzymes in food processing to date has involved destroying the structural integrity of the cell wall so it was indeed surprising when it was discovered that cell wall fragments could be selectively digested, leaving intact cell walls unaffected. The present invention offers a quick, easy, and inexpensive process for improving the appearance and quality of produce that has been cut or peeled while also significantly prolonging its shelf-purchase life.